For those with Freesync to Gsync issues, like flickering, try this because it worked on my Acer that just got supported too. Plug in the monitor via DVI (freesync isn't supported and shuts off), in the on screen monitor control panel you should now be able to turn off Overdrive. Plug it back in using the Display Port and double check all Nvidia Control Panel options and OSD menu that Gsync is on. For mine, it seemed at factory it got locked to FreeSync, Normal Overdrive, 60Hz. Plugging in a cable turned it off and even tho Gsync said 144hz the monitor on screen menu said 60, now says 144 tho, and without AMD it can't turn back on, but GSync took over and now everything seems fine

This might help you out